diff --git a/components/db_ido_mysql/idomysqlconnection.cpp b/components/db_ido_mysql/idomysqlconnection.cpp
index fa4361ac7..093fb651b 100644
--- a/components/db_ido_mysql/idomysqlconnection.cpp
+++ b/components/db_ido_mysql/idomysqlconnection.cpp
@@ -233,6 +233,7 @@ void IdoMysqlConnection::ClearConfigTables(void)
 {
 	/* TODO make hardcoded table names modular */
 	ClearConfigTable("commands");
+	ClearConfigTable("comments");
 	ClearConfigTable("contact_addresses");
 	ClearConfigTable("contact_notificationcommands");
 	ClearConfigTable("contactgroup_members");
@@ -246,6 +247,7 @@ void IdoMysqlConnection::ClearConfigTables(void)
 	ClearConfigTable("hostgroup_members");
 	ClearConfigTable("hostgroups");
 	ClearConfigTable("hosts");
+	ClearConfigTable("scheduleddowntime");
 	ClearConfigTable("service_contactgroups");
 	ClearConfigTable("service_contacts");
 	ClearConfigTable("servicedependencies");
diff --git a/components/db_ido_pgsql/idopgsqlconnection.cpp b/components/db_ido_pgsql/idopgsqlconnection.cpp
index 56320fc98..a0eb66df5 100644
--- a/components/db_ido_pgsql/idopgsqlconnection.cpp
+++ b/components/db_ido_pgsql/idopgsqlconnection.cpp
@@ -237,6 +237,7 @@ void IdoPgsqlConnection::ClearConfigTables(void)
 {
 	/* TODO make hardcoded table names modular */
 	ClearConfigTable("commands");
+	ClearConfigTable("comments");
 	ClearConfigTable("contact_addresses");
 	ClearConfigTable("contact_notificationcommands");
 	ClearConfigTable("contactgroup_members");
@@ -250,6 +251,7 @@ void IdoPgsqlConnection::ClearConfigTables(void)
 	ClearConfigTable("hostgroup_members");
 	ClearConfigTable("hostgroups");
 	ClearConfigTable("hosts");
+	ClearConfigTable("scheduleddowntime");
 	ClearConfigTable("service_contactgroups");
 	ClearConfigTable("service_contacts");
 	ClearConfigTable("servicedependencies");
diff --git a/lib/db_ido/servicedbobject.cpp b/lib/db_ido/servicedbobject.cpp
index 1f84cd7be..55be48822 100644
--- a/lib/db_ido/servicedbobject.cpp
+++ b/lib/db_ido/servicedbobject.cpp
@@ -211,14 +211,6 @@ void ServiceDbObject::OnConfigUpdate(void)
 	/* service dependencies */
 	Log(LogDebug, "db_ido", "service dependencies for '" + service->GetName() + "'");
 
-	DbQuery query_del1;
-	query_del1.Table = GetType()->GetTable() + "dependencies";
-	query_del1.Type = DbQueryDelete;
-	query_del1.Category = DbCatConfig;
-	query_del1.WhereCriteria = make_shared<Dictionary>();
-	query_del1.WhereCriteria->Set("dependent_service_object_id", service);
-	OnQuery(query_del1);
-
 	BOOST_FOREACH(const Service::Ptr& parent, service->GetParentServices()) {
 		Log(LogDebug, "db_ido", "service parents: " + parent->GetName());
 
@@ -276,14 +268,6 @@ void ServiceDbObject::OnConfigUpdate(void)
 	/* custom variables */
 	Log(LogDebug, "db_ido", "service customvars for '" + service->GetName() + "'");
 
-	DbQuery query_del2;
-	query_del2.Table = "customvariables";
-	query_del2.Type = DbQueryDelete;
-	query_del2.Category = DbCatConfig;
-	query_del2.WhereCriteria = make_shared<Dictionary>();
-	query_del2.WhereCriteria->Set("object_id", service);
-	OnQuery(query_del2);
-
 	Dictionary::Ptr customvars;
 
 	{
@@ -292,7 +276,7 @@ void ServiceDbObject::OnConfigUpdate(void)
 	}
 
 	if (customvars) {
-		ObjectLock olock (customvars);
+		ObjectLock olock(customvars);
 
 		String key;
 		Value value;
@@ -317,8 +301,6 @@ void ServiceDbObject::OnConfigUpdate(void)
 	}
 
 	/* update comments and downtimes on config change */
-	RemoveComments(service);
-	RemoveDowntimes(service);
 	AddComments(service);
 	AddDowntimes(service);
 
diff --git a/lib/icinga/service.cpp b/lib/icinga/service.cpp
index 532aa1dc0..3a45529c2 100644
--- a/lib/icinga/service.cpp
+++ b/lib/icinga/service.cpp
@@ -48,9 +48,6 @@ void Service::Start(void)
 
 	VERIFY(GetHost());
 
-	SetSchedulingOffset(Utility::Random());
-	UpdateNextCheck();
-
 	AddDowntimesToCache();
 	AddCommentsToCache();
 
@@ -78,6 +75,11 @@ void Service::OnConfigLoaded(void)
 		m_Host->AddService(GetSelf());
 
 	UpdateSlaveNotifications();
+
+	SetSchedulingOffset(Utility::Random());
+
+	if (GetNextCheck() < Utility::GetTime() + 300)
+		SetNextCheck(Utility::GetTime() + Utility::Random() % 300);
 }
 
 Service::Ptr Service::GetByNamePair(const String& hostName, const String& serviceName)